Apparatus for depositing solid carbon dioxide

ABSTRACT

An apparatus is provided for an improvement in the production of solid carbon dioxide in the form of a fine powder referred to herein as snow which comprises a control valve and a nozzle positioned upstream from the control valve which is suitable for releasing compressed liquid carbon dioxide to produce the carbon dioxide snow. The preferred form of control valve is a rotary ball valve.

United States Patent Gateshill et a1.

[ 51 Sept. 16, 1975 APPARATUS FOR DEPOSITING SOLID CARBON DIOXIDEInventors: Henry Charles Gateshill,

Rotherham; Norris Wilfred Shepherd, Worksop, both of England Assignee:Air Products and Chemicals, Inc.,

Allentown, Pa.

Filed: Dec. 21, 1973 Appl. No.: 427,398

Foreign Application Priority Data June 1, 1973 United Kingdom 26349/73US. Cl 239/573; 239/551 Int. Cl. B05B 01/30 Field of Search 239/562,550, 569, 551, 239/572, 573; 62/384, 514, 63, 74, 64;

[56] References Cited I UNITED STATES PATENTS 2,109,966 3/1938 Breitmann169/74 2,289,352 7/1942 Ensminger... 169/11 2,457,526 12/1948 Brown239/574 3,447,755 6/1969 Cartwright 239/551 Primary Examiner.lohn J.Love Attorney, Agent, or FirmRichard A. Dannells; Barry Moyerman [5 7ABSTRACT 10 Claims, 2 Drawing Figures L ATENTEU SEP 1 6 75 SHEET 2 0F 2APPARATUS FOR DEPOSITING SOLID CARBON DIOXIDE BACKGROUND OF THEINVENTION The present invention relates to apparatus for depositingsolid carbon dioxide in the form of a fine powder hereinafter calledsnow.

within the bore and terminating in an expanding head defining the saidpassage. The spindle is preferably movable axially relative to thehousing to enable control or adjustment of the passage cross-section.However, the present invention in broad terms is not limited toapparatus employing such a nozzle but can employ any type of nozzlesuitable for releasing compressed liquid carbon dioxide to producecarbon dioxide snow.

It has been found that a considerable problem arises in switching thecarbon dioxide snow on and off particularly where this is done rapidlyand successively e.g., by an automatic trip mechanism. Thus, when anon/off valve situated in the liquid carbon dioxide line is switched off,liquid carbon dioxide tends to remain between the control valve and thenozzle and in the nozzle itself and this tends to solidify and block thepassage.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided apparatus for the production of carbon dioxide snowcomprising a nozzle connected upstream of a control valve. The controlvalve should be ofa type capable of resisting the full pressure of theliquid carbon dioxide in the off position and should afford a throughpassage of a sufficiently large cross-sectional area as to offersubstantially no resistance to the flow of carbon dioxide snow whenopen.

The preferred form of control valve is a rotary ball valve. Such ballvalves are well-known commercial products and comprise a rotatable steelball having a through passage and fitting in a seat in a tubular duct sothat in the off position the through passage is at right angles to theduct and in the on position it is aligned axially with the duct.Conventional ball valves of this type normally have a through passage ofrestricted diameter relative to the duct but the preferred ball valveused in the present invention has a through passage which is ofsubstantially the same diameter as the duct, so that in the openposition a virtually unobstructed passage is presented to the snowleaving the nozzle.

The duct in the control valve preferably has substantially the samediameter as the adjacent end of the mouth of the nozzle, and the duct inthe control valve preferably has a counterbore into which the nozzle isdirectly secured.

While clearly a shut-down valve is preferably inserted in the input lineto the nozzle for use when the nozzle is out of operation for longperiods, while the nozzle is in the course of intermittent use theliquid carbon dioxide is fed unobstructed to the nozzle and the flow isentirely controlled by the control valve downstream of the nozzle.

The control valve, particularly in the form of a rotary ball valve asdescribed, is conveniently operated by means of a pneumatic orelectrical actuator and a plurality of nozzle and valve combinations maybe con- 5 trolled from a single actuator. The preferred form ofapparatus employs a central actuator, preferably of the pneumatic type,connected to a pair of nozzle/valve combinations, one on each side.

A short expansion head may be secured tothe downstream end of thecontrol valve duct, e.g., by having a tubular spigot secured in acounterbore in that end of the duct.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment is hereafterdescribed with reference to the accompanying drawings, in which FIGS. 1and 2 areside elevational views of a nozzle and valve assembly inaccordance with the invention, FIG. 1 showing the open condition of thevalves and FIG. 2

20 showing the closed condition of the valves.

DETAILED DESCRIPTION OF THE INVENTION AND DRAWINGS The assemblyillustrated comprises a central pneumatic actuator I of a standardcommercial type employing a through axle 2 which rotates 90 between endpositions mounted to each side of. the actuator, in line with the axle2, by means of brackets 3, is a pair of rotary ball valves 4, 4 whichare identical Worcester ball valves modified in that the throughpassages 5, 5 in the balls 6, 6' are bored out to the same diameter asthe ducts 7, 7 of the valves. The balls 6, 6' are secured to respectiveaxles 8, 8 which are connected to respective ends of the axle 2 by meansof couplings 9, 9.

The upstream ends 10, I of the ducts 7, 7 of the valves are counterboredand into these counterborcs are secured the mouth ends of nozzles 11, IIfor producing carbon dioxide snow from liquid carbon dioxide suppliedunder pressure through pipes I2, 12' from a single pipe 13 with ashut-down valve 14. The mouth 15, 15 of the nozzles are clear of theballs 6, 6 of the valves 4, 4', and the ducts 7, 7 have the samediameter as the adjacent ends of the mouths.

The downstream ends l6, 16' of the ducts 7, 7' of the valves arecounterbored and threaded to receive externally threaded tubular spigotsl7, 17 of expansion heads 18, 18 having frusto-conical inner surfacesI9, 19.

In operation the actuator l is energised by air or (conveniently)gaseous carbon dioxide supplied through a pipe 20, to rotate the balls6, 6 synchronously from the closed position (FIG. 2) to the openposition (FIG. I) and viceversa. In the closed condition of the valves4, 4 the nozzle mouths 15, 15 and upstream portions of the ducts 7, 7are filled with liquid carbon dioxide. When the valves are opened, theliquid carbon dioxide expands through the nozzles and forms snow whichpasses through the passages 5, and the downstream portions of the ductsto the expansion heads I8, 18'. The amount of liquid carbon dioxidepresent between the mouths 15, of the nozzles I I, l l and the balls 6,6 when the valves are closed has been found to be insufficient tointerfere with the normal operation of the nozzles in producing snow.However, it is desirable to keep the volume between the nozzles 11, 11and the ball to a minimum, and so the nozzle mouths 15, 15' may bebrought closer to the balls 6, 6 than shown in the drawings.

We claim: 1. An apparatus for the production of carbon dioxide snowwhich comprises:

a. a rotary ball control valve comprising 1. a seat, 2. a rotatable ballfitted into said seat, said ball having a through passage therein, and3. a duct having substantially the same diameter as said. throughpassage and being axially aligned with said through passage when saidcontrol valve is in an on position, and b. a nozzle having a boreterminating in an outwardly expanding mouth, the adjacent end of whichis connected upstream of said control valve. 7 2. The apparatus as inclaim I wherein said duct has substantially the same diameter as theadjacent end of said mouth.

3. The apparatus as in claim 2 wherein said duct has a counterbore intowhich said nozzle is directly secured.

4. The apparatus as in claim 1 wherein an expansion head is secured tothe downstream end of said duct.

5. The apparatus as in claim 4 wherein said expansion head has a tubularspigot secured in a counterbore in the downstream end of said duct.

6. The apparatus as in claim 1 wherein an input line is connected tosaid nozzle for supplying liquid carbon dioxide thereto and wherein ashut-down valve is inserted in saidinput line.

7. The apparatus as in claim 1 wherein said control valve is operated bymeans of an actuator.

8. The apparatus as in claim 7 wherein a plurality of nozzle and valvecombinations are controlled from a single actuator.

9. The apparatus as in claim 1 wherein said nozzle comprises a hollowhousing member having a central bore terminating is said outwardlyexpanding mouth and a spindle centrally supported within said bore andterminating in an expanding head defining an annular passage with saidbore.

10. The apparatus as in claim 9 wherein said spindle is movable axiallyrelative to said housing to enable control of the cross-sectional areaof said annular pas-

1. AN APPARATUS FOR THE PRODUCTION OF CARBON DIOXIDE SNOW WHICHCOMPRISES: A. A ROTARY BALL CONTROL VALVE COMPRISING
 1. A SEAT,
 2. AROTATABLE BALL FITTED INTO SAID SEAT, SAID BALL HAVING A THROUGH PASSAGETHEREIN, AND
 2. The apparatus as in claim 1 wherein said duct hassubstantially the same diameter as the adjacent end of said mouth.
 2. arotatable ball fitted into said seat, said ball having a through passagetherein, and
 3. a duct having substantially the same diameter as saidthrough passaGe and being axially aligned with said through passage whensaid control valve is in an on position, and b. a nozzle having a boreterminating in an outwardly expanding mouth, the adjacent end of whichis connected upstream of said control valve.
 3. The apparatus as inclaim 2 wherein said duct has a counterbore into which said nozzle isdirectly secured.
 3. A DUCT HAVING SUBSTANTIALLY THE SAME DIAMETER ASSAID THROUGH PASSAGE AND BEING AXIALLY ALIGNED WITH SAID THROUGH PASSAGEWHEN SAID CONTROL VALVE IS IN AN ON POSITION, AND B. A NOZZLE HAVING ABORE TERMINATING IN AN OUTWARDLY EXPANDING MOUTH, THE ADJACENT END OFWHICH IS CONNECTED UPSTREAM OF SAID CONTROL VALVE.
 4. The apparatus asin claim 1 wherein an expansion head is secured to the downstream end ofsaid duct.
 5. The apparatus as in claim 4 wherein said expansion headhas a tubular spigot secured in a counterbore in the downstream end ofsaid duct.
 6. The apparatus as in claim 1 wherein an input line isconnected to said nozzle for supplying liquid carbon dioxide thereto andwherein a shut-down valve is inserted in said input line.
 7. Theapparatus as in claim 1 wherein said control valve is operated by meansof an actuator.
 8. The apparatus as in claim 7 wherein a plurality ofnozzle and valve combinations are controlled from a single actuator. 9.The apparatus as in claim 1 wherein said nozzle comprises a hollowhousing member having a central bore terminating is said outwardlyexpanding mouth and a spindle centrally supported within said bore andterminating in an expanding head defining an annular passage with saidbore.
 10. The apparatus as in claim 9 wherein said spindle is movableaxially relative to said housing to enable control of thecross-sectional area of said annular passage.